This invention relates to safety devices for seats. More particularly, this invention relates to improvements in safety devices for ejection seats in aircraft.
Aviation is one of the true marvels of modern man. Defying gravity through the use of high-powered machinery allows man to travel at great speed and great altitudes over great distances. However, as will be appreciated, the speeds and altitudes reached in connection with aviation pose a significant safety risk to human occupants in the event of mechanical failure, the compromising of the integrity of the aircraft, severely inclement weather, or other catastrophic events that could lead to the aircraft crashing or exploding.
The risks posed upon aircraft occupants are particularly acute in connection with high-performance aircraft and military aircraft. These vehicles are subjected to the most dangerous speeds and conditions known in the art. For example, military aircraft must be fast aircraft to maneuver as necessary in battle, must enter areas of hostile fire, and must be prepared to fly and land in the most difficult of weather and terrain conditions. Numerous artisans have labored to provide aircraft with the most advanced engineering advantages to ensure its occupants with the greatest chances of success in battle while minimizing the dangers inherent in hostile aviation.
Recognizing the inability to ensure the safe landing of aircraft, some prior artisans focused on methods and devices for allowing occupants to exit the aircraft with the greatest hopes of survival given the speeds and altitudes faced. Early innovations were made in the technology of parachutes. In theory, by making parachutes available to aircraft occupants, the occupants could don the parachutes and bail out of the aircraft at a sufficient altitude to allow them to float to the ground and avoid death or serious bodily injury. Unfortunately, as will be appreciated, not all occupants have the time to retrieve a parachute or reach an exit in the event of a catastrophic event. This proved to be particularly true as aircraft and anti-aircraft weaponry became more sophisticated and escape times much shorter.
In an effort to overcome the inability of occupants to maneuver to an exit to quickly egress from an aircraft, other prior artisans developed the ejection seat. An ejection seat allows a seat occupant to eject the seat and themself from the aircraft extremely quickly. An ejection seat is a complex device with numerous cooperating systems. In theory, the seat provides an automatic ejection sequence for an aircraft occupant, such as a military crewmember. The sequence starts when the crewmember pulls the firing control handle on the seat. The mode of operation is selected and controlled by a recovery sequencer. The sequencer provides the best recovery means for the full range of escape conditions. Three modes of operation are available. The mode selected depends on aircraft speed and altitude at the time of ejection.
Again, as will be appreciated, as the speed and conditions faced by modern aircraft became more hazardous, improvements in the protection offered by ejection seats was necessary. A particular feature of ejection seats that required modernization was the inertia reel harness assembly. The supersonic speeds and G-forces seat occupants are exposed to necessitates a mechanism be provided to prevent occupants from succumbing to forward g-force motion and injuring themselves. Also, the force and speed that an ejecting pilot is exposed to upon rocket-propelled expulsion from the aircraft would surely result in neck and spinal injury unless a mechanism is provided to secure the pilot to the seat back. Typically, these two hazards are dealt with by a properly functioning inertia reel harness assembly.
As illustrated in FIG. 1, the inertia reel harness assembly is located in the center of the seat back below the headrest. The inertia reel fulfills two function: (1) it acts like the shoulder belt in a car, restraining the pilot against a forward (xe2x88x92x) motion, and (2) upon ejection, it retracts the pilot to an upright posture to minimize the possibility of spinal damage due to spinal misalignment upon catapult ignition. With modern aircraft, the left side of the seat bucket is provided with a handle that allows the crewmember to manually lock the reel prior to intense maneuvers or landing to prevent possible injuries resulting from not being securely fastened in the seat.
Inertia reels have become a critical component of seats in modern aviation. The proper function of these reels has posed significant problems in the art due to their constant maintenance requirements. For example, as will be appreciated, inertia reels are monitored for proper functioning and settings including inspection of the control cam lever assembly and the mechanism cover for loose and/or missing screws. Specifically, it is recommended that inertia reel straps be inspected every 30 days, and replaced at a minimum of every two years. It is further recommended that inertia reels be replaced upon the occurrence of any of the following conditions: 1) the inertia reel straps extend more than two inches with the inertia reel control handle in the locked position; or 2) the inertia reel straps extend less than 36 inches when pulled with the control handle in the unlocked position. It is recommended to at least service the inertia reel upon the occurrence of any of the following: 1) the inertia reel straps do not retract freely into inertia reel when released in the unlocked position; 2) the inertia reel straps do not retract back into the inertia reel and lock in the retracted position when straps are released from the extended position with control handle in the locked position; 3) the inertia reel control assembly binds; 4) the inertia reel does not lock automatically preventing further extension of straps with the inertia reel control in the unlocked position and the straps are extended rapidly in one motion and 5) inertia reel straps become worn or frayed.
Heretofore, in order to inspect and/or replace the inertia reel or any of the components of the inertia reel assembly, technicians typically employed a tedious multi-step process. This process may be expressed with reference to FIGS. 1A to 1E. In accordance with that process the technicians must first access the inertia reel assembly. To access the assembly, technicians first remove the recovery parachute assembly, remove the drogue parachute assembly, remove the drogue gun, and remove the environmental sensor. Next, technicians release mortar control cable 14, shoulder restraint cable 15 and ground service release cable 16 by removing screw 5, securing clamp 8 and spacer 6; removing screw 9, nut 11 and washer 10 securing clamps 12 and 13. Tube assembly 26 is then disconnected and removed from the inertia reel 36 and the technician plugs the tube assembly and caps the inertia reel inlet. Cotter pin 27 and washer 28 are then removed from lever 31. Next, tape is removed from screws 23 on the front side of the seat to allow removal of screws 23 and washers 24 from the seat. It is then recommended to cut and remove the sealant between fairing 25 and the seat structure and carefully remove fairing 25. It is only after the foregoing tedious procedure is complete that the technician has access to the inertia reel and can inspect, repair and/or replace the inertia reel in accordance with conventional procedures.
Utilizing the foregoing process, replacement of the inertia reel and/or the inertia reel straps takes the technician approximately 12-16 hours, most of which is spent gaining access to the inertia reel. As a result, ejection seats undergoing maintenance are out of commission for nearly two days. Over 8,000 ACES II ejection seats are currently in use by the United States Air Force and by the air defense fleets of over 20 other countries. Accordingly, the down time created by inertia reel repair/replacement using heretofore employed methods is detrimental to the readiness of the seat, the aircraft and the fleet and could lead to catastrophic results in the event of a crisis.
Accordingly, notwithstanding the existence of the above-described methods, a need still exists to modify existing aircraft seats to provide ready access to the inertia reel. There is also a need for a modified ejection seat that facilitates rapid access to the inertia reel.
It is an object of the invention to reduce the time needed to service inertia reels of ejection seats.
Another object of the invention is to make the servicing of inertia reels in ejection seats less complicated.
Still another object of the invention is to improve access to inertia reels mounted in ejection seats.
Yet another object of the invention is to reduce down time of aircraft that employ ejection seats having inertia reels.